A power storage module for vehicles such as electric vehicles or hybrid vehicles includes multiple power storage elements having positive electrode terminals and negative electrode terminals. The power storage elements are arranged such that electrode terminals of adjacent power storage elements are connected with a bus bar and the power storage elements are connected in series or in parallel.
In the power storage module, there has been known a technology that each bus bar is held with an insulation film sheet included in the connection module (for example, refer Patent Document 1) for easy operation of mounting each bus bar on the electrode terminals.
[Patent Document 1] Japanese Unexamined Patent Application Publication No. 2014-175291
The bus bar module (the connection module) described in Patent Document 1 includes an insulation film sheet (hereinafter, referred to as a sheet member) that is made of expandable synthetic resin. If an interval between the electrodes of adjacent power storage elements (an electrode pitch) is varied, the sheet member made of expandable synthetic resin may follow the variation of the interval. However, each of the bus bars that are bonded on the sheet member may be moved independently if the sheet member, which is expandable and soft, is expanded or contracted. Therefore, the movement of each bus bar cannot be assumed. It is necessary to control positions of the bus bars to follow a tolerance of the electrode pitch of the power storage module. However, the positions of the bus bars cannot be controlled and therefore, the connection module including the sheet member may not be properly mounted in a power storage element group.
In the connection module described in Patent Document 1, the connection module is mounted in the power storage element group such that the electrode (a bolt) of a battery is tightened up with the sheet member and the nut. Therefore, a tightening force of the sheet member is decreased due to lowering of reaction force of the sheet member after the tightening, and the bolt may loosen by vibration. If the bolt loosens, the reliability of mounting of the connection module on the power storage element group may be lowered.
In this specification, there is provided a connection module that can follow a tolerance of an electrode pitch in an arrangement direction of power storage elements of a power storage element group and keep reliability of mounting of the connection module on the power storage element group with a simple structure.